Study Of Online Monotoring And Protection System For EPON Based On OTDR

With the development of smart grid, remote medical service and cloud computation, copper cables will finally be replaced by optical fibers. Nowadays, Passive Optical Network (PON), especially Ethernet Passive Optical Network (EPON), becomes more and more popular due to its high bandwidth, high reliability and low cost, which make it one of the most suitable technologies for service providers to solve the"last mile"problem.However, Statistics show that most of the faults in optical networks are link failures, which will disturb network using and even cause financial loss. With the improvement of users'rights awareness and relative specifications, service providers will pay much more for the network failure. So, it is important to find a way to efficiently monitor links and localize faults, and to improve network reliability with certain protection strategies.Nowadays, researches about monitoring system based on OTDR for PON cannot solve problems such as overlay of otdr traces, attenuation of monitoring signals and dark fiber monitoring at the same time. As a result, by improving existed designs, the author has proposed a novel online monitoring and protection system based on OTDR for EPON. With the GIS management system based on redeveloped GE Smallworld PNI, it becomes a complete monitoring system which can rapidly localize fault points on fibers. The system implements both online monitoring and backup protection strategy, and it can solve the problems such as overlay of otdr traces, attenuation of monitoring signals and dark fiber monitoring at the same time. The experiments have proved that the system can realize online monitoring, but cannot achieve fast protection switch due to design defects.As a result, the author has then proposed an online monitoring and protection system with Network Management System for EPON. The system works with EPON NMS, and it can realize real-time fault detection via SNMP protocol. Experiment result shows that the system can achieve fast protection switch. Finally, it has solved the previous problem of slow switch time, while kept the advantages of the previous system.At last, the authors has explained the design and realization of the GIS management system, mainly including the design purpose, relative algorithm, flow diagram. Test results show that the system can respond to NMS alarm, and achieve protection switch and fault alert.